uglymemo (empty) → 0.1.0.0

raw patch · 3 files changed

+41/−0 lines, 3 filesdep +basedep +containerssetup-changed

Dependencies added: base, containers

Files

• Data/MemoUgly.hs +24/−0
• Setup.hs +2/−0
• uglymemo.cabal +15/−0

@@ -0,0 +1,24 @@+module Data.MemoUgly(memoIO, memo) where+import Control.Concurrent.MVar+import qualified Data.Map as M+import System.IO.Unsafe(unsafePerformIO)++-- | Memoize the given function by allocating a memo table,+-- and then updating the memo table on each function call.+memoIO :: (Ord a)+       => (a -> b)           -- ^Function to memoize+       -> IO (a -> IO b)+memoIO f = do+    v <- newMVar M.empty+    let f' x = do+            m <- readMVar v+            case M.lookup x m of+                Nothing -> do let { r = f x }; m <- takeMVar v; putMVar v (M.insert x r m); return r+                Just r  -> return r+    return f'++-- | The pure version of 'memoIO'.+memo :: (Ord a)+     => (a -> b)           -- ^Function to memoize+     -> (a -> b)+memo f = let f' = unsafePerformIO (memoIO f) in \ x -> unsafePerformIO (f' x)

@@ -0,0 +1,2 @@+import Distribution.Simple+main = defaultMain

@@ -0,0 +1,15 @@+Name:                uglymemo+Version:             0.1.0.0+Synopsis:            A simple (but internally ugly) memoization function.+Description:         A simple (but internally ugly) memoization function.+License:             PublicDomain+Author:              Lennart Augustsson+Maintainer:          lennart@augustsson.net+Category:            Data+Build-type:          Simple+Cabal-version:       >=1.2+++Library+  Exposed-modules:     Data.MemoUgly+  Build-depends:       base < 10, containers